The invention relates to a force sensor, in particular for detecting forces on a vehicle seat, which by utilizing electrical or electromagnetic effects outputs an electrical signal which corresponds to a compressive force, tensile force or bending force acting on the force sensor.
In many fields in mechanics, force sensors are needed which even at relatively inaccessible places in equipment or assemblies are meant to enable precise determination of the tensile and/or compressive forces. An electrical signal corresponding to the force measurement is intended to be available for further processes of evaluation or regulation. In the field of automotive electronics, for instance, such force sensors can often be used, but the force sensors used until now are mostly relatively large, and the production process is relatively expensive.
For some important electronic systems in the motor vehicle, such as for belt restraint systems, a small, compact force sensor is needed. Precisely at the connecting points between components, at which points the force is concentrated, force measuring bolts as a component of the force sensor are of particular importance. For instance, for measuring the force of the weight on a seat and its distribution, which is measured at the connection to the seat, a force sensor is needed which can be mass produced economically in large numbers. But in the fields of production and quality measurement as well, precise force sensors that measure statically are increasingly needed.
From International Patent Disclosure WO 00/16054 A1, a measurement pickup for detecting motion in a vehicle seat is known, in which an elastic deformation of a supporting element is detected by the measurement cell between an upper frame, including the seating shell, and a lower frame, secured to the floor of the vehicle, optionally also via a mechanism for longitudinal and vertical adjustment.
It is also known per se for such a measurement cell to have a Hall element with an integrated circuit connected to it, with which element a magnetic field that is altered because of a mechanical deformation can be evaluated. Until now, in the known embodiment, the self-diagnosis that is important for reliable function, such as the diagnosis pertaining to security against mispolarization and the diagnosis of the sensor connection, the bond pins, and other IC-specific details, has been limited to the integrated sensor circuit (sensor IC).